A. Field of the Invention
This invention relates to crosslinkable elastomeric interpolymers comprising a major proportion of one or more olefins and one or more esters of acrylic acid and a minor proportion of a vinyl aromatic compound having a halomethyl group substituted for one of the aromatic ring hydrogens.
More particularly, this invention relates to interpolymers, having elastomeric properties when crosslinked by means of nucleophilic reagents, said interpolymers prepared with the aid of a catalyst system comprising a Lewis acid and a free-radical generator from monomers comprising one or more acyclic or alicyclic olefins; one or more acyclic or alicyclic esters of acrylic acid wherein the acyclic or alicyclic radical moiety is free of olefinic unsaturation or readily replaceable halogen; and from 0.3 to 30 mol percent of the total monomers present in said interpolymer of a halomethylated aromatic vinyl compound.
Most particularly, this invention relates to interpolymers, having elastomeric properties when cross-linked by means of one or more nucleophilic reagents, prepared with the aid of a catalyst system comprising a Lewis acid and an organic peroxide comprising (A) about 50 mol percent of one or more C.sub.1 to C.sub.20 acyclic or alicyclic esters of acrylic acid in which the C.sub.1 to C.sub.20 acyclic or alicyclic ester radical moiety is free of olefinic unsaturation or readily replaceable halogen; and a total of about 50 mol percent of the sum of: (B) one or more C.sub.2 to C.sub.20 acyclic or alicyclic Type I (R--CH.dbd.CH.sub.2) or Type III (R(R')C.dbd.CH.sub.2) monoolefins wherein R and R' are independently selected from the group consisting of hydrogen, and C.sub.1 to C.sub.18 straight and branched chain alkyl radicals, aryl, alkylaryl, arylalkyl and cycloalkyl radicals; and (C) 0.3 to 30 mol percent, preferably not more than 10 mol percent (in the total interpolymer) of one or more halomethylated aromatic vinyl compounds.
While the preferred method for the preparation of the interpolymers of this invention is from the said monomers, an alternative method comprises polymerizing (A) one or more C.sub.1 to C.sub.20 acyclic or alicyclic esters of acrylic acid in which the C.sub.1 to C.sub.20 ester radical moiety is free of olefinic unsaturation or readily replaceable halogen; (B) one or more C.sub.2 to C.sub.20 acyclic or alicyclic Type I or Type III monoolefins; 0.3 to 30 mol percent of an aromatic vinyl compound, followed by halomethylation of the aromatic ring in the interpolymer.
The interpolymers of this invention may be blended, prior to crosslinking, with halogenated polymers such as halogenated polyolefins; halogenated butyl rubber; halogenated terpolymers such as the brominated EPDM described in U.S. Pat. No. 3,524,826; sulfochlorinated polyolefin elastomers such as hypalon; polychloroprenes such as neoprene; polyvinyl chloride; epichlorohydrin rubbers. Such blends may also include process oils, plasticizers, resins, fillers and reinforcing agents. The crosslinked elastomers of this invention possess a high tensile strength, elongation and modulus and are useful as general or special purpose elastomers.
The highly reactive nature of the halogen in a halomethyl group attached to an aromatic ring not only facilitates crosslinking at moderate vulcanization temperatures but provides a means for conversion of the halomethyl moiety to a variety of derivatives having increased utility. Generally, the use of a difunctional nucleophilic reagent leads to crosslinking, while a monofunctional nucleophilic reagent gives substituted derivatives. Particularly useful as difunctional reagents are diamines, and their derivatives, and ureas, thioureas, and their mono- and dialkylated reaction products. For example, reaction of the interpolymers of this invention with reagents well known to those having ordinary skill in the chemical arts permits conversion of the halomethyl group to a cyanomethyl group; hydroxymethyl group; carboxymethyl group; aldehyde group; thiomethyl group; aminomethyl group; alkoxymethyl group; methylene ester of a carboxylic acid; quaternary nitrogen halides and the like. It is possible by suitable adjustment of the ratio of the polymer and the difunctional nucelophilic reagent to obtain substituted polymer derivatives rather than crosslinked products. Derivatives containing residual halomethyl groups may be further reacted, with for example, difunctional reagents to give crosslinked networks. And the substituted products, for example, the hydroxymethyl and aminomethyl derivatives may be crosslinked with a dibasic acid or anhydride, or by reaction of the carboxylic acid derivative with a glycol. The utility of the interpolymers of this invention is very broad as is evident from this discussion.
B. Prior Art
Copolymers of alkyl acrylates with chlorine containing monomers are old in the art. For example, copolymers of ethyl acrylate with from 2.5 to 5 percent of 2-chloroethyl acrylate or 2-chloroethyl vinyl ether have been available commercially as Lactoprene EV since 1944.
Similar copolymers of alkyl acrylates with vinyl chloroacetates are disclosed in U.S. Pat. No. 3,201,373.
U.S. Pat. No. 3,578,636 discloses alternating interpolymers of an olefin or halogenated olefin with an acrylate ester or halogenated ester of acrylic acid.
U.S. Pat. No. 3,629,215 discloses alternating interpolymers of alpha-olefins, halo-olefins and alpha or beta substituted acrylic compounds.
U.S. Pat. No. 3,635,924 describes the preparation of copolymers from halo-olefins and acrylic compounds.
Belgian Pat. No. 763,733 discloses interpolymers of an olefin, a saturated or unsaturated alkyl acrylate and a halogenated ester or ether such as 2-chloroethyl acrylate or 2-chloroethyl vinyl ether.
Netherlands Pat. No. 7,204,702 discloses copolymers of ethylene with vinyl chloride, vinyl chloroacetate and 2-chloroethyl acrylate.